error: add return_handle_error(value, handle, [error]) macro

This macro validates that `handle` is valid. If `handle` is valid, it
behaves just like `return_error(value, [error])`. If `handle` is
invalid, it sets errno to EBADF and GetLastError() returns
ERROR_INVALID_HANDLE.

src/error.c

@@ -119,3 +119,23 @@ void err_set_win_error(DWORD error) {
     SetLastError(error);
   errno = err_map_win_error_to_errno(error);
 }
+
+int _check_handle(HANDLE handle) {
+  DWORD flags;
+
+  /* GetHandleInformation() succeeds when passed INVALID_HANDLE_VALUE, so check
+   * for this condition explicitly. */
+  if (handle == INVALID_HANDLE_VALUE)
+    return_error(-1, ERROR_INVALID_HANDLE);
+
+  if (!GetHandleInformation(handle, &flags))
+    return_error(-1);
+
+  return 0;
+}
+
+void err_validate_handle_and_set_win_error(HANDLE handle, DWORD error) {
+  if (_check_handle(handle) < 0)
+    return;
+  err_set_win_error(error);
+}

src/error.h

@@ -11,10 +11,19 @@
     err_set_win_error(error);              \
     return (value);                        \
   } while (0)
-
 #define return_error(value, ...) _return_error_helper(__VA_ARGS__ + 0, value)
 
+#define _return_handle_error_helper(error, value, handle)          \
+  do {                                                             \
+    err_validate_handle_and_set_win_error((HANDLE) handle, error); \
+    return (value);                                                \
+  } while (0)
+#define return_handle_error(value, handle, ...) \
+  _return_handle_error_helper(__VA_ARGS__ + 0, value, handle)
+
 WEPOLL_INTERNAL errno_t err_map_win_error_to_errno(DWORD error);
 WEPOLL_INTERNAL void err_set_win_error(DWORD error);
+WEPOLL_INTERNAL void err_validate_handle_and_set_win_error(HANDLE handle,
+                                                           DWORD error);
 
 #endif /* WEPOLL_ERROR_H_ */